Overview

The main aim of this project is to use genetic data from wild duiker feces to test the role of historical climate change, rivers and habitat differences in shaping the evolution of tropical forest duikers. Forest duikers constitute an important part of central African rainforest communities and are an extremely rich group with as many as 18 species in the genus Cephalophus across Africa. They also make excellent models for testing hypotheses of tropical diversification owing to their tight association with forest habitats and their prevalence throughout much of the Congo basin. Duikers are also an important source of protein and as a result are of conservation concern due to heavy hunting pressure. Accordingly, this project has adopted a non-invasive sampling strategy in which geo-referenced DNA is obtained from fresh feces collected from multiple sites across Central Africa.

1. To determine the best conditions for efficient recovery of DNA from samples stored in the field for several weeks or more prior to extraction

2. To develop an efficient method for the identification of duiker species from sequences obtained from their feces since most duikers are impossible to differentiate based on pellet morphology alone

Having accomplished these two major project goals we are currently gathering data from mitochondrial and nuclear markers to test the following hypotheses:

Pleistocene refuge hypothesis: Contraction of forest into isolated pockets of suitable habitat during Pleistocene ice ages led to the fragmentation and subsequent diversification of forest duiker species

Riverine barrier hypothesis: Major rivers such as the Ogooué and Ivindo in Gabon and the Sanaga river in Cameroon led to the separation and differentiation of duiker populations on different river banks

Ecological gradient hypothesis: Areas of transition from contiguous forest to forest-savanna mosaic have led to the genetic differentiation of duiker populations across these zones of ecological transition

This study is the first of its kind to compare patterns of genetic variation across an entire community of forest mammals and promises to provide exciting insights into the origin and maintenance of species diversity in tropical rainforests.

In central African forests, duikers in the genus Cephalophus form part of a rich community of tropical forest artiodactyls that also include the pygmy antelope (Neotragus batesi), bushbuck (Tragelaphus scriptus), sitatunga (Tragelaphus spekei) and the water chevrotain (Hyemoschus aquaticus). Together these species constitute an important source of protein and are heavily hunted for their meat throughout central Africa (Wilkie & Carpenter, 1999; Newing, 2001; Brashares et al., 2004; Laurance et al., 2006). Duikers are small to medium in size and are typically found in tropical forests and woodland mosaics of sub-Saharan Africa. Duikers are ruminants and possess a multiple chambered stomach, enabling them to effectively digest plant tissue. At least 18 species of duiker have been described (e.g. Kingdon, 1997), of which 17 belong to the genus Cephalophus and one to the genus Sylvicapra. Mitochondrial analysis splits these species into four major groups: the conservative dwarf clade (C. monticola, C. maxwelli), the giant duiker clade (C. silvicultor, C. spadix, C. dorsalis, C. jentinki), the east African red duiker clade (C. leucogaster, C. rufilatus, C. nigrifrons, C. natalensis, C. harveyi) and west African red duiker clade (C. callipygus, C. weynsi, C. ogilbyi, C. rubidus and C. niger) leaving C. zebra and C. adersi as a separate but only weakly supported lineage (Jansen van Vuuren and Robinson, 2001). However, the taxonomy of duikers is still relatively poorly understood and this number can vary depending on the classification scheme used. The name “duiker” is Afrikaans for diver, referring to their tendency to use their powerful hind-legs to dive into the underbrush in response to threat. The horns of duikers are small, back-pointing, and close to the skull, which ensures that they do not get tangled in the thick underbrush of the forest. Fruit makes up an important part of the diet of many species although the composition of the diet may vary with season (see Feer, 1989). With the exception of the blue duiker (Cephalophus monticola), duikers are generally solitary and can be nocturnal, diurnal or active during the day and night (Dubost, 1983a, b; Bowland and Perrin, 1995). They also make extensive use of preorbital scent glands as a means of social communication (Dubost, 1983a).